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3상 PFC 기능을 갖는 소형풍력발전기용 AC-DC 컨버터
곽상현(Sang-hyun Kwak),최미선(Mi-seon Choi),문준선(Joon-sun Moon),오용승(Yong-Seung Oh),안강순(Kang-Soon Ahn) 전력전자학회 2011 전력전자학술대회 논문집 Vol.2011 No.7
본 논문은 영구 자석형 동기 발전기(PMSG)를 사용하는 소형풍력발전기의 고조파 제거 및 단위 역률 효과를 갖는 AC-DC 컨버터에 관한 내용이다. 가변속도로 제어되는 풍력발전기는 입력전압 및 전류에 많은 고조파 성분을 가지고 있다. 제안된 컨버터는 단일 스위치를 갖는 3상 승압형 정류기 형태로 인덕터 전류가 불연속모드(DCM)로 동작되며, 입력전류의 고조파를 제거하여 단위 역률을 갖는 단상 220V, 3㎾의 소형 풍력발전기용 컨버터이다.
곽상현(Sang-hyun Kwak),김기선(Ki-seon Kim),김대경(Dae-kyong Kim),차현록(Hyun-rok Cha),박성준(Sung-jun Park) 전력전자학회 2009 전력전자학술대회 논문집 Vol.2009 No.1
산업 분야의 전반에 걸쳐 IT화가 요구되고 있으며, 고역률 디지털화 AC/DC 컨버터의 디지털 제어에 관한 연구가 활발히 이루어지고 있다. 기존의 아날로그 제어방식의 고역률 AC/DC컨버터는 입력전압에 노이즈가 포함될 경우 컴포넌트의 변화가 입력전압의 변화에 매우 민감하게 작용하는 단점을 가지고 있다. 본 논문에서는 고역률 AC/DC 컨버터를 구성함에 있어 디지털 제어방식을 기본으로한 마이크로프로세서를 사용하고, 그 특성을 개선하기 위해 인덕터 및 부하전류에 대한 전향 제어기를 설계하였다. 또한 마이크로프로세서 사용에 의한 고역률 AC/DC 컨버터는 부하 변화에 전원전압의 고조파 성분에 관계없이 고역률을 이룰 수 있음을 시뮬레이션을 통하여 검증 하였다.
곽상현(Sang Hyun Kwak),문영민(Young Min Moon),이영우(Young Woo Lee),문인석(In Seok Moon) 대한두개저학회 2017 대한두개저학회지 Vol.12 No.1
Vestibular schwannoma and pituitary adenoma are intracranial tumors with different histological characteristics, and coexistence of these tumors is very rare. The concurrent presence case of these tumors firstly reported in the literature at 1985 by Gorman. Over the years, there have been a few case-reports for concurrent presence of these tumors. However, the association between these tumors have not been established. Here, we report a 53 years-old male patient case who was diagnosed with vestibular schwannoma and coexistence of pituitary adenoma.
차진욱 ( Jin Wook Cha ),곽상현 ( Sang Hyun Kwak ),김석재 ( Seok Jai Kim ),김창모 ( Chang Mo Kim ),정성태 ( Sung Tae Jeong ),배홍범 ( Hong Beom Bae ),유경연 ( Kyung Yeon Yoo ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.51 No.5
A tracheal bronchus is an aberrant, accessory or ectopic bronchus arising almost always from the right lateral wall of the trachea at the level less than 2 cm above the carina. An endotracheal or endobronchial tube can obstruct or migrate into a tracheal bronchus, resulting in pulmonary atelectasis, hypoxemia, or both during general anesthesia. We report two patients in whom the anomalous tracheal bronchus had been surgically resected under general anesthesia. The anomaly was identified before surgery in each patient and anesthesia was uneventful. (Korean J Anesthesiol 2006; 51: 638~40)
문준선(Joon-sun Moon),곽상현(Sang-hyun Kwak),최미선(Mi-seon Choi),오용승(Yong-Seung Oh),안강순(Kang-Soon Ahn) 전력전자학회 2011 전력전자학술대회 논문집 Vol.2011 No.7
본 논문에서는 고전력 밀도 및 고효율을 목표로 한 ㎿급 풍력발전용 전력변환장치 시스템을 제안한다. 이 시스템은 스텍을 병렬로 구성하여 시스템의 전체 효율을 높였으며 LCL 필터 및 수냉식 방열 방식을 사용하여 시스템의 사이즈를 줄임으로서 전력밀도를 향상시켰다. 제안된 시스템의 타당성을 검증하기 위하여 500㎾급 스텍 4병렬을 이용하여 ㎿급 풍력발전 전력변환 장치 시스템을 제작 및 실험하였다.
임상연구 : Propofol 마취 유도 후 후두경을 이용한 기관내 삽관시 나타나는 혈역학반응을 둔화하기 위한 Remifentanil의 적정용량
차진욱 ( Jin Wook Cha ),곽상현 ( Sang Hyun Kwak ),김석재 ( Seok Jai Kim ),최정일 ( Jeong Il Choi ),김창모 ( Chang Mo Kim ),정성태 ( Sung Tae Jeong ),유경연 ( Kyung Yeon Yoo ) 대한마취과학회 2006 Korean Journal of Anesthesiology Vol.51 No.3
Background: A laryngoscopy and endotracheal intubation cause an increase in the blood pressure and heart rate. Remifentanil is an opioid that is often used to reduce the hemodynamic responses after tracheal intubation. This study evaluated the effect of three bolus doses of remifentanil on the hemodynamic responses to a laryngoscopy and tracheal intubation. Methods: Eighty patients, aged 35-65 years, with an ASA physical status of I and II were randomly divided into four groups containing 20 patients each. Anesthesia was induced with propofol 2 mg/kg followed 30 s later by saline (control) or remifentanil 0.5 (R0.5), 1 (R1) or 2 (R2) μg/kg given as a bolus over a 30 s period. A laryngoscopy and tracheal intubation were performed 90 s later (corresponding to 3 min after induction), and anesthesia was maintained using 2% sevoflurane and 50% nitrous oxide in oxygen. Rocuronium 1 mg/kg was given as a neuromuscular block. The systolic arterial blood pressure (SAP) and heart rate (HR) were recorded until 5 min after intubation. Results: In all groups, the SAP decreased after inducing anesthesia and then increased after intubation in all groups (P < 0.05), but the maximum increases (46, 15, and 9 mmHg in the R0.5, R1, and R2 groups, respectively) after intubation were lower in the remifentanil groups than that of the control group (73 mmHg) (P < 0.05). The HR decreased in the remifentanil groups while it remained stable in the controls after the induction of anesthesia. However, it increased after intubation in all groups. The mean maximum HR (83, 71, and 69 bpm in the R0.5, R1 and R2 groups, respectively) was significantly lower in the remifentanil groups than that in the controls (98 bpm) (P < 0.05). All remifentanil doses significantly attenuated the pressor and tachycardiac responses (P < 0.05). Conclusions: All remifentanil doses were effective in controlling the pressor and tachycardiac response to endotracheal intubation in patients in whom anesthesia was induced with propofol. However, the use of the 1 and 2μg/kg dose was associated with a decrease in the SAP to less than 85 mm Hg in 10 patients (50%) each. Therefore, 0.5μg/kg appears to be the optimal dose to attenuate the cardiovascular responses to endotracheal intubation in patients. (Korean J Anesthesiol 2006; 51: 292~6)
임상연구 : Doxapram Hydrochloride가 후두마스크기도를 이용한 전 정맥마취 시 환기반응에 미치는 영향
윤영철 ( Young Chul Yoon ),곽상현 ( Sang Hyun Kwak ),정성태 ( Sung Tae Jeong ),김석재 ( Seok Jai Kim ),배홍범 ( Hong Beom Bae ),정성수 ( Sung Su Chung ),정창영 ( Chang Young Jeong ) 대한마취과학회 2007 Korean Journal of Anesthesiology Vol.53 No.4
Background: Intravenous anesthetics causes depression of ventilatory response to hypercapnea. Doxapram stimulates ventilation via peripheral and central chemoreceptors. This study was aimed to evaluate the effect of doxapram on ventilation during total intravenous anesthesia (TIVA). Methods: 60 patients undergoing operation under spontaneous ventilation via laryngeal mask airwaywere randomly divided into 3 groups: Control group received 5% dextrous infusion, D-2 group received doxapram injection of 1 mg/kg followed by continuous infusion of 2 mg/kg/hr, and D-4 group received doxapram injection of 2 mg/kg followed by continuous infusion of 4 mg/kg/hr. Anesthesia was induced and maintained with propofol and remifentanil. Respiratory rate, tidal volume (VT) and arterial carbon dioxide tension (PaCO2) were measured before and 15 min after induction of anesthesia, 0(15 min after start of operation), 1, 2, 3, 5, 15, 30, 45, and 60 min after start of doxapram infusion during TIVA. Results: VT was significantly increased 1 min after start of doxapram infusion and returned to the value of pre-doxapram infusion immediately. In D-4 group, VT was significantly (P<0.05) increased again 5 min after doxapram infusion compared with the value of pre-doxapram infusion and control group. PaCO2 was decreased 1 min after start of doxapram infusion and then increased again 2 min after doxapram infusion. In D-4 group, the degree of increase of PaCO2 was significantly (P<0.05) less than those of D-2 group. Conclusions: Doxapram injection of 2 mg/kg followed by continuous infusion of 4 mg/kg/hr improved the depression of ventilatory response during TIVA. (Korean J Anesthesiol 2007; 53: 470∼6)